DA helps your domain to do better in search results if you are higher than your competitors. If your DA is 50 and your competitor's is 40, then it is very likely you beat such provided you have done your on-page optimization. PA is the same method except that it handles Pages.

Page Authority is a score (on a 100-point scale) developed by Moz that predicts how well a specific page will rank on search engines. It is based off data from the Mozscape web index and includes link counts, MozRank, MozTrust, and dozens of other factors. Domain Authority is a score (on a 100-point scale) developed by Moz that predicts how well a website will rank on search engines.

Domain Authority (DP)domain authority is to give an estimated prediction regarding the performance that a website gives in its SERP rankings, thus this happens to be one of the most important target of Search Engine Optimization oriented companies based on the web. It basically happens to be a calculated metric that calculates the prospects of a particular website or web page to feature in the first page of Google.Page Authority (PA)I think page authority is more important for search engines in general because they analyze precisely the page from the backlinks come. But of course, page authority depends on domain authority.

Domain authority is a measure of the power of a domain name and is one of many search engine ranking factors. Domain authority is based on three factors: Age, Popularity, and Size.

SEO gurus Moz can be credited with the metric known as DA or domain authority. Moz’s own search algorithm gauges the quality of any given site based on a huge complex combination of factors including onsite and offsite, taking in to account things such as diversity of Backlinking domains to come up with a score between 0 and 100. A brand new site, for example, will have 0 whereas a very high authority site might have 80/100. Domain Authority gives those working in the field of online marketing a useful metric by which to consider the apparent quality of any site.

DA : the dropping of updates to Page Rank by Google, Domain Authority would soon become one of the key metric to gauge the quality of your website, often needed by advertisers.PA : Page Authority measures the predictive ranking strength of a single page, Domain Authority measures the strength of entire domains or subdomains.

The High authority websites are very helpful while link building. Any website's SERP can be improve easily by building high authority backlinks. That's why, it is very improtant as an SEO point of view.

Domain Authority: A score out of 100-points representing the likelihood for arbitrary content to rank on this domain.Page Authority: A score out of 100-points representing the likelihood for arbitrary content to rank on this page.

Page Authority is a score developed by Moz that predicts how well a specific page will rank on search engines. It is based off data from the Mozscape web index and includes link counts, MozRank, MozTrust, and dozens of other factors.

Domain Authority is a score developed by Moz that predicts how well a website will rank on search engines.